A data transmission method, apparatus, and system are provided that relate to the communications field and that reduce core network bandwidth resources occupied by data transmission. The method includes receiving, by a first base station, a request message sent by a first device, where the request message carries identification information of requested data and identification information of the first device, and the first device includes a user equipment or a second base station; retrieving, by the first base station, in stored data according to the identification information of the requested data; and when matched data is retrieved, sending, by the first base station, the matched data to the first device according to the identification information of the first device, where the matched data refers to data that matches the identification information of the requested data.